Methods and systems for receiver initiated protection of a wireless communication exchange

ABSTRACT

Systems, methods, and devices for wireless communication are disclosed. In some aspects, a method includes receiving from a transmitting device, via a receiving device, a first wireless frame, the first wireless frame forming at least a portion of a wireless communication exchange between the transmitting device and the receiving device, transmitting to the transmitting device, in response to the first wireless frame, a second wireless frame indicating that the receiving device will enable protection for a remaining portion of the wireless communication exchange, transmitting during a contention period, in response to the indication, a frame reserving the wireless medium for a time period; and receiving, via the receiving device, the remaining portion of the wireless communication exchange from the transmitting device during the time period.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/116,293, filed Feb. 13, 2015, and entitled “METHODS AND SYSTEMS FORRECEIVER INITIATED PROTECTION OF A WIRELESS COMMUNICATION EXCHANGE.” Thedisclosure of this prior application is considered part of thisapplication, and is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present application relates generally to wireless communications,and more specifically to systems, methods, and devices for protecting awireless medium from collisions or for helping the transmitter to gainaccess to the medium during a wireless communication exchange between atransmitter and a receiver.

BACKGROUND

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks may be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN),wireless local area network (WLAN), or personal area network (PAN).Networks also differ according to the switching/routing technique usedto interconnect the various network nodes and devices (e.g., circuitswitching vs. packet switching), the type of physical media employed fortransmission (e.g., wired vs. wireless), and the set of communicationprotocols used (e.g., Internet protocol suite, SONET (SynchronousOptical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

A device on a wireless network may experience collisions, especially indense network environments. In some cases, the frequency of collisionsmay prevent the device from communicating effectively on the wirelessnetwork. In certain other case the device may not be able to access themedium for long periods of time due to continuous access of hiddennodes. Thus, there is a need to improve the reliability of devicestransmitting within dense network environments.

SUMMARY OF THE INVENTION

The systems, methods, and devices of the invention each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this invention as expressed bythe claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this invention provide advantages that include improvedcommunications between first and second devices in a wireless network.In an embodiment, the first and second devices may be access points andstations (STAs) in the wireless network.

One aspect disclosed is a method of wireless communication on a wirelessmedium, the method comprising receiving, by a receiving device, a firstwireless frame from a transmitting device during a contention period,the first wireless frame forming a portion of a wireless communicationexchange between the transmitting device and the receiving device,transmitting during the contention period, a second wireless frameindicating a network allocation vector for the wireless medium should beset for a time period of a duration sufficient to protect a remainingportion of the wireless communication exchange from packet collisions,and receiving, via the receiving device, the remaining portion of thewireless communication exchange from the transmitting device during thetime period.

In some aspects, the wireless communication exchange includes one ormore wireless frames with a more data indication, and correspondingacknowledgments for the one or more wireless frames. In some aspects,the method also includes determining that the first wireless frameincludes an error, wherein the transmitting of the second wireless frameis in response to the determining. In some aspects, the method includestransmitting to the transmitting device, in response to the firstwireless frame, a third wireless frame indicating that the receivingdevice will protect the wireless medium for the remaining portion of thewireless communication exchange. In some aspects, the method includesdecoding the first wireless frame to determine the transmitting devicerequests that the receiving device protect the wireless medium for theremaining portion of the wireless communication exchange; andtransmitting the second wireless frame in response to the determination.In some aspects, the method includes generating the third wireless frameto indicate a time when the receiving device will protect the wirelessmedium. In some aspects, the method includes generating the thirdwireless frame to indicate one or more transmission parameters for thetransmitting device. In some aspects, the one or more transmissionparameters include one or more of a modulation and coding scheme, use ofLDPC/BCC, a number of spatial streams, a transmission bandwidth, orchannel information, or a channel allocation for the transmission of theremaining portion of the wireless communication exchange, etc.

Another aspect disclosed is an apparatus for wireless communication on awireless medium. The apparatus includes a receiver configured to receivea first wireless frame from a transmitting device during a contentionperiod, the first wireless frame forming at least a portion of awireless communication exchange between the transmitting device and theapparatus; and a transmitter configured to transmit during thecontention period, a second wireless frame indicating a networkallocation vector for the wireless medium is set for a time period of aduration sufficient to protect a remaining portion of the wirelesscommunication exchange from packet collisions; and completing thewireless communication exchange during the time period.

In some aspects of the apparatus, the wireless communication exchangeincludes one or more wireless frames with a more data indication, andcorresponding acknowledgments for the one or more wireless frames. Insome aspects, the apparatus also includes a processor configured todetermine that the first wireless frame includes an error, wherein thetransmitter is further configured to transmit the second wireless framein response to the determining.

In some aspects, the apparatus also includes transmitting to thetransmitting device, in response to the first wireless frame, a thirdwireless frame indicating that the apparatus will transmit the secondwireless frame. In some aspects, the apparatus also includes a processorconfigured to decode the first wireless frame to determine thetransmitting device requests that the apparatus set the networkallocation vector for the time period for the duration sufficient toprotect the remaining portion of the wireless communication exchangefrom packet collisions. In some aspects, the apparatus also includes aprocessor configured to generate the third wireless frame to indicateone or more transmission parameters for the transmitting device, whereinthe one or more transmission parameters include one or more of amodulation and coding scheme, a transmission bandwidth, channelinformation, and a channel allocation.

In some aspects, the apparatus includes a processor configured togenerate the third wireless frame as one of a block acknowledgment or anegative acknowledgment. In some aspects, the apparatus includes aprocessor configured to generate the third wireless frame to indicate atime when the apparatus will transmit the second wireless frame. In someaspects, the apparatus includes a processor configured to generate thethird wireless frame to indicate one or more transmission parameters. Insome aspects, the apparatus includes a processor configured to generatethe third wireless frame to indicate a duration of time for which thenetwork allocation vector will be set. In some aspects, the apparatusincludes a processor configured to determine a time necessary tocomplete the wireless communication exchange, and generate the secondwireless frame to protect the wireless medium for at least the timenecessary. In some aspects of the apparatus, the transmitter is furtherconfigured to transmit the second wireless frame protecting the wirelessmedium as a clear-to-send frame intended for the transmitting device (ofthe first wireless frame), the clear-to-send frame indicating a durationgreater than or equal to a time necessary to transmit the remainingportion. In another aspect of the apparatus, the transmitter is furtherconfigured to transmit the second wireless frame protecting the wirelessmedium as a trigger frame, indicating a duration greater than or equalto a time necessary to transmit the remaining portion, the transmitparameters (e.g., MCS, BW, resource allocation [the channel allocationto be used for delivering the wireless frame], etc), wherein the triggerframe enables for transmission, after a predefined time (e.g., SIFS),one or more wireless devices in SU mode or MU mode, wherein the firstwireless device is part of the one or more wireless devices.

Another aspect disclosed is a method of wireless communication over awireless medium. The method includes transmitting, by a transmittingdevice, a first wireless frame to a receiving device during a contentionperiod, the first wireless frame comprising a portion of a wirelesscommunication exchange between the transmitting device and the receivingdevice, receiving a second wireless frame from the receiving device, thesecond wireless frame indicating a network allocation vector should beset for a time period, and completing, by the transmitting device, thewireless communication exchange with the receiving device during thetime period.

In some aspects, the method also includes generating the first wirelessframe to comprise an indication of a request for the receiving device toset the network allocation vector. In some aspects, the method alsoincludes receiving, from the receiving device, a third wireless framedifferent than the second wireless frame, the third wireless framecomprising an indication that the receiving device will request thenetwork allocation vector be set; and in response to the third wirelessframe, deferring further transmissions of the wireless communicationexchange until the network allocation vector is set. In some aspects,the method also includes decoding the third wireless frame to determineone or more of a confirmation of transmission parameters included in thefirst wireless frame, and one or more transmission parameters fortransmission to the receiving device.

In some aspects, the method also includes: generating the first wirelessframe as a data frame with a more data indication, wherein completingtransmission of the wireless communication exchange comprisestransmitting one or more additional data frames and receivingcorresponding acknowledgments for the one or more additional dataframes.

Another aspect disclosed is an apparatus for wireless communication overa wireless medium. The apparatus includes a transmitter configured totransmit a first wireless frame to a receiving device during acontention period, the first wireless frame comprising a portion of awireless communication exchange between the apparatus and the apparatus,a receiver configured to receive a second wireless frame indicating anetwork allocation vector should be set for a time period, andcompleting the wireless communication exchange with the receiving deviceduring the time period. In some aspects, the apparatus also includes aprocessor configured to generate the first wireless frame to comprise anindication of a request for the receiving device to set the networkallocation vector. In some aspects, the apparatus also includes aprocessor, wherein the receiver is further configured to receive a thirdwireless frame comprising an indication that the receiving device willset the network allocation vector, and the processor is configured to,in response to the third wireless frame, defer further transmissions ofthe wireless communication exchange until the network allocation vectoris set. In some aspects, the processor is further configured to decodethe third wireless frame to determine one or more of a confirmation oftransmission parameters included in the first wireless frame, and one ormore transmission parameters for transmission to the receiving device.In some aspects, the apparatus also includes a processor configured togenerate the first wireless frame as a data frame with a more dataindication, wherein completing transmission of the wirelesscommunication exchange comprises transmitting one or more additionaldata frames and receiving corresponding acknowledgments for thetransmitted data frames.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary wireless communication system 100.

FIG. 2 shows an exemplary functional block diagram of a wireless device202 that may be employed within the wireless communication system ofFIG. 1.

FIG. 3 is a timing diagram of one embodiment of a wireless communicationexchange between an access point and a station (STA).

FIG. 4A is another timing diagram of one embodiment of a wirelesscommunication exchange between an access point and a station.

FIG. 4B is another timing diagram of one embodiment of a wirelesscommunication exchange between an access point and a station.

FIG. 5A shows an example of a media access control frame.

FIG. 5B shows an example of a trigger frame.

FIG. 5C shows an example of a response frame.

FIG. 6 is a flowchart of a method of wireless communication.

FIG. 7 is a flowchart of a method of wireless communication.

FIG. 8A shows an organization of a wireless frame.

FIG. 8B shows another organization of a wireless frame.

FIG. 9 is a flowchart of a method of determining whether a frame thatincludes errors is addressed to a device receiving the frame.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to any specific structureor function presented throughout this disclosure. Rather, these aspectsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the disclosure to those skilled in theart. Based on the teachings herein one skilled in the art shouldappreciate that the scope of the disclosure is intended to cover anyaspect of the novel systems, apparatuses, and methods disclosed herein,whether implemented independently of, or combined with, any other aspectof the invention. For example, an apparatus may be implemented or amethod may be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein may be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Popular wireless network technologies may include various types ofwireless local area networks (WLANs). A WLAN may be used to interconnectnearby devices together, employing widely used networking protocols. Thevarious aspects described herein may apply to any communicationstandard, such as a wireless protocol.

In some aspects, wireless signals in a sub-gigahertz band may betransmitted according to the 802.11 protocol using orthogonalfrequency-division multiplexing (OFDM), frequency division multiplexing(FDM), time division multiplexing (TDM), direct-sequence spread spectrum(DSSS) communications, a combination of OFDM and DSSS communications,multi user (MU, multi-input multi output (MIMO)), or other schemes whichcan be used for single user (SU) or multi user (MU) communications.Implementations of the 802.11 protocol may be used for high efficiency,very high throughput, real time communications, sensors, metering, andsmart grid networks. Advantageously, aspects of certain devicesimplementing the 802.11 protocol may consume less power than devicesimplementing other wireless protocols, and/or may be used to transmitwireless signals across a relatively long range, for example about onekilometer or longer. Devices may also realize more efficient wirelesscommunication due to reduced probability of collisions when utilizingthe disclosed methods and systems.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there may betwo types of devices: access points (“APs”) and clients (also referredto as stations, or “STAs”). In general, an AP may serve as a hub or basestation for the WLAN and a STA serves as a user of the WLAN. Forexample, a STA may be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, a STA connects to an AP via aWiFi (e.g., Institute of Electronical and Electronic Engineers (IEEE)802.11 protocol such as 802.11) compliant wireless link to obtaingeneral connectivity to the Internet or to other wide area networks. Insome implementations a STA may also be used as an AP.

An access point (“AP”) may also comprise, be implemented as, or known asa NodeB, Radio Network Controller (“RNC”), eNodeB, Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, orsome other terminology.

A station “STA” may also comprise, be implemented as, or known as anaccess terminal (“AT”), a subscriber station, a subscriber unit, amobile station, a remote station, a remote terminal, a user terminal, auser agent, a user device, user equipment, or some other terminology. Insome implementations an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein may beincorporated into a phone (e.g., a cellular phone or smartphone), acomputer (e.g., a laptop), a portable communication device, a headset, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a gaming device or system, a global positioning system device,or any other suitable device that is configured to communicate via awireless medium.

As discussed above, wireless devices operating within dense networks mayat times experience packet collisions caused by transmissions of otherdevices operating on the same wireless medium and at times may not evenbe able to access the medium due to continuous usage of the medium byother devices. These collisions may degrade the communicationsefficiency of the wireless device and the wireless network as a whole.In some scenarios, a receiving device may experience a higher frequencyof collisions than a transmitting device during a communicationsexchange between the two devices. In these scenarios, while thetransmitting device may be able to contend for the wireless medium withan acceptable efficiency, the receiver's efficiency may be below anacceptable level. For example, a station in communication with an accesspoint may transmit a frame when its random back-off expires. If thestation is operating on a wireless medium with high utilization, theremay be a high likelihood that this transmission will fail due tocollisions with hidden nodes. Similarly such failures may be caused dueto interference, channel conditions or wrong selection of transmitparameters by the transmitting device.

Upon detection of the failed transmission, the station may retransmitthe frame after restarting its back-off timer. The restarted back-offtimer may utilize a new random value that is larger than the previousrandom value, in some cases selected from a range of values that isdouble the previous range of values. Thus, time to gain access to themedium by the station is substantially increased in the presence ofcollisions. In some aspects, the station may retransmit the message at alower data rate to increase the likelihood that the retransmission doesnot fail. This further compromises the media effective capacity for thestation. In some instances, the station may experience continuouscollisions, such that the station is essentially “starving” for mediumaccess. The disclosed methods and systems resolve these issues,resulting in increased throughput, reduced latency, and increasednetwork efficiency.

In particular, in the instances described above, it may be desirable forthe receiving device to enable the access to the medium for thetransmitting device and/or to protect the communication exchange withthe transmitting device and reduce a frequency of collisions experiencedby the receiving device during the exchange. Similarly, in somescenarios the transmitter may not be able to gain access to the mediumsuch that it may transmit a frame to an intended receiver due tocontinuous usage of the medium by other devices. In these scenarios, itmay be desirable for the receiver to enable access to the medium for thetransmitting device as described herein.

The disclosed methods and systems provide for requesting and receivingprotection of a medium during a wireless communication exchange. In someaspects, a device transmitting data requests that a device to which thetransmitted data is addressed initiate the protection of the medium.This may differ from traditional methods that typically may have adevice that intends to transmit data (for example, transmit a datamessage to a receiving device) also initiate protection for the data(for example, by transmitting a request to send message). Receiverinitiated protection, as described above, may be particularly beneficialwhen a medium environment in proximity to a transmitter of the data issubstantially different from the medium environment in proximity to thereceiver of the data. For example, in some aspects, the receiver of thedata may be experiencing a relatively high level of packet collisions,whereas the transmitter of the data may be experiencing a rather lowerlevel of packet collisions. Therefore, in some aspects, it may be moreeffective for the receiver of the data to initiate the protectioninstead of the transmitter. For example, in some aspects, thetransmitter may be effectively hidden from other devices with which itstransmissions may be colliding. In other words, it may be desirable toinitiate protection for a communication exchange at a device closest inproximity to potential collision inducing devices, or by a device withthe highest likelihood of reaching potential collision inducing devices,such that those devices are more likely to receive frames indicating theprotection (such as a request to send and/or clear to send) and settheir network allocation vector appropriately. Thus, the disclosedmethods and systems recognize that, unlike traditional methods, it isnot always most effective for a transmitter of data to initiateprotection for the data, but may be, in some situations, more effectivefor a transmitter to ask the receiver of the data to initiate theprotection, and thus reach potential collision inducing nodes within atransmit range of the receiver.

There are several different types of wireless communication exchangesthat may be protected by the methods and systems described herein. Forexample, one wireless communication exchange that may be protected is asequence of data frames, with most of the data frames including a “moredata” indication (except perhaps the last data frame that is part of theexchange). In this example, the transmitter of the data frames mayrequest the receiver of the data frames to initiate the protection forthe sequence of data frames or at least a portion of the sequence ofdata frames. The exchange may also include acknowledgements or blockacknowledgments corresponding to each of the data frames.

More generally, a wireless communication exchange may take the form, insome embodiments, of: FRAME 1∥SIFS∥(Optional [ACK1, NACK1, BlockAck1]) .. . [PREDEFINED TIME], FRAME 2∥SIFS2∥FRAME 3∥[ACK2, NACK2, BA2]. Theunderlined portion may have multiple occurrences in some aspects. In theabove generalized description, the PREDEFINED TIME is short interframespace (SIFS), or PCF Interframe Space (PIFS), or after EnhancedDistributed Channel Access (EDCA) contention. (also the above SIFS canbe the predefined time).

FRAME 1 may be transmitted by/from a transmitter to a receiver: In someaspects, FRAME 1 may include an indication of a request for protectionof the communication exchange. FRAME 1 may include a request forprotection in several different ways depending on the embodiment. Forexample, if FRAME 1 contains one or more errors in portions of it whenit is received (e.g., one or more MPDUs contained in it may be corrupted(i.e., one or more FCS fails), then this may be interpreted as a requestfor protection in some aspects. Alternatively, FRAME 1 may include anexplicit indication of a request for protection. For example, in someaspects, a particular field in FRAME 1, if set to a predefined value,may be a request for protection. Some implementations may utilize aRetry bit of FRAME 1 for this indication. In some aspects, if Frame 1contains an indication of additional data to be delivered to therecipient (More Data bit, Queue Size in the QoS Control field, BufferSize in the HT Control field), this may indicate a request forprotection of the wireless communication exchange. In some aspects, anexplicit frame type is defined to request protection. For example, anRTS frame may fit into this category. In the above description, theACK1, NACK1, BA1 are sent from the receiving device (the deviceacknowledging the data) to the transmitting device (the devicetransmitting the data).

In the above example of a wireless communication exchange, Frame 2 istransmitted from the receiver to transmitter (and can be addressed tomultiple transmitters if, for example, it is a trigger frame). Frame 2may be a clear-to-send frame that is transmitted with a receiver addressfield set to the transmitter address field (a so called “CTS-To Self”),a Trigger frame (which can be addressed to one or more transmitters (oneof which is “our” transmitter, an MU PPDU that contains one or more(A-)MPDUs, which can contain the Trigger frame as one or more of theMPDUs, or may contain the trigger information in the MAC header of theMPDUs, etc. In some aspects, Frame 2 may function to replace the ACK1,NACK, BA1 in the sequence. FRAME 3 may be sent from the transmitter tothe receiver (and may be sent in a multi user PPDU, in some aspectsalong with frames from other transmitters, if the FRAME 1 includessubchannel allocations, and other TX parameters, for sending theframes).

In some aspects, FRAME 3 includes one or more MPDUs which are derivedfrom the information indicated or obtained from Frame 1 (e.g., one ormore MPDUs could be the ones that failed one transmitted in Frame 1, orwhose presence was indicated in Frame 1 etc. ACK2, NACK2, or BA2 may betransmitted from the receiver to the transmitter.

Enabling access to the medium may include transmitting a message fromthe receiver to the transmitter that allows the transmitter to discardor otherwise ignore previously set network allocation vector (NAV)durations or deferral mechanisms and access the medium to initiate thecommunications exchange within a predefined time after reception of theframe that is transmitted by the receiver. The pre-defined time may beshort interframe space (SIFS), point coordination function (PCF)Interframe Space (PIFS) or some known duration of time. Protection ofthe communication exchange may include transmitting one or more messagesthat cause devices on the medium (and receiving the messages) to settheir NAV for a duration of time. The network allocation vector (NAV)may be a virtual carrier-sensing mechanism used to limit the need forphysical carrier-sensing at a wireless air interface in order to savepower. For example, in some aspects, a MAC layer frame header maycontain a duration field that specifies the transmission time requiredfor a frame or series of frames, in which time the medium will be busy.In another example, a PHY layer frame header may contain a durationfield, wherein the duration field may be located in the L-SIG or in theSIG-A portion of the PHY header. Stations listening on the wirelessmedium read the duration field and set their network allocation vector,which is an indicator for a station on how long it must defer fromaccessing the medium.

In some aspects, the network allocation vector may be implemented as acounter, which counts down to zero at a uniform rate. When the counteris zero, the virtual carrier sense mechanism provided by the NAVindicates that the medium is idle. When the NAV is non-zero, thisindicates that the medium is busy.

Messages that set network allocation vectors may include, for example,clear-to-send messages and/or trigger messages (wherein in this contexta trigger message enables the one or more intended receivers of thetrigger to transmit their data within a predetermined period of timefollowing the trigger, wherein the data is transmitted in single user orin multi user mode (i.e., in specified time/space/frequencies providedby the trigger frame itself), or Null Data Packets (e.g, a frame thatconsists only of the PHY header contents). Transmission of thesemessages may inhibit transmissions of those devices (that are not theintended receiver(s) of the messages) for the duration, thus reducingthe number of packet collisions experienced by the receiving deviceduring the duration of time. Since the receiving device transmits themessages in some of the disclosed aspects, a first set of wirelessdevices may receive the messages as compared to a second set of devicesthat may receive similar messages transmitted by the transmittingdevice. This may be advantageous in some scenarios. For example, if adevice that is somewhat distant from a transmitting device is includedin the first set of devices but not in the second set of devices,transmissions by the transmitter distant device may not be inhibited ifthe transmitting device transmits the NAV setting messages (because thetransmitter distance device may not receive the messages—due to itsdistance from the transmitter). Note that within the followingdescription, one that is skilled in the art may realize that referenceto a single transmitter may include any number of transmitters. Forexample, when a particular disclosed message is sent by a device, thedevice may enable a multitude of transmitters to transmit following themessage as described herein.

Additionally, in some aspects, an intended receiver device oftransmissions may be in a better position to determine whethertransmissions are being successfully received by it than thetransmitting device. Thus, the receiving device may conditionapplication of the disclosed techniques, which may cause a NAV to beset, on whether packets transmitted/received during a contention periodare successfully received by the device. Thus, the receiving device maybe able to apply knowledge that the transmitting device is unable toapply. Thus, setting the NAV to protect a communication exchange may beperformed only when necessary, thus improving the ability of devices onthe medium to coexist and increasing medium utilization generally.

Thus, when the receiving device transmits the disclosed NAV settingmessages, there may be an increased probability that the receiver willexperience improved efficiency as compared to methods that provide forthe transmitting device to set the NAV.

FIG. 1 shows an exemplary wireless communication system 100. Thewireless communication system 100 may operate pursuant to a wirelessstandard, for example the 802.11 standards. The wireless communicationsystem 100 may include an AP 104, which communicates with STAs 106.

A variety of processes and methods may be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs 106.For example, signals may be sent and received between the AP 104 and theSTAs 106 in accordance with OFDM/OFDMA techniques. If this is the case,the wireless communication system 100 may be referred to as anOFDM/OFDMA system. Alternatively, signals may be sent and receivedbetween the AP 104 and the STAs 106 in accordance with Code DivisionMultiple Access (CDMA) techniques. If this is the case, the wirelesscommunication system 100 may be referred to as a CDMA system. Maybe goodto specify MU, SU and MIMO here as well, and FDM and FDMA, bothmulticarrier and single carrier.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106 may be referred to as a downlink (DL) 108,and a communication link that facilitates transmission from one or moreof the STAs 106 to the AP 104 may be referred to as an uplink (UL) 110.When the link is between one STA and a peer STA it is referred to assingle user (SU) while a link between one STA and one or more STAs isreferred to multi user (MU). Alternatively, a downlink 108 may bereferred to as a forward link or a forward channel, and an uplink 110may be referred to as a reverse link or a reverse channel.

The AP 104 may act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. The AP 104 along with theSTAs 106 associated with the AP 104 and that use the AP 104 forcommunication may be referred to as a basic service set (BSS). It shouldbe noted that the wireless communication system 100 may not have acentral AP 104, but rather may function as a peer-to-peer networkbetween the STAs 106. Accordingly, the functions of the AP 104 describedherein may alternatively be performed by one or more of the STAs 106.

The AP 104 may transmit a beacon signal (or simply a “beacon”), via acommunication link such as the downlink 108, to other nodes STAs 106 ofthe system 100, which may help the other nodes STAs 106 to synchronizetheir timing with the AP 104, or which may provide other information orfunctionality. Such beacons may be transmitted periodically. In oneaspect, the period between successive transmissions may be referred toas a superframe or as a beacon interval. Transmission of a beacon may bedivided into a number of groups or intervals. In one aspect, the beaconmay include, but is not limited to, such information as timestampinformation to set a common clock, a peer-to-peer network identifier, adevice identifier, capability information, a superframe or beaconinterval duration, transmission direction information, receptiondirection information, a neighbor list, and/or an extended neighborlist, some of which are described in additional detail below. Thus, abeacon may include information both common (e.g., shared) amongstseveral devices, and information specific to a given device.

In some aspects, a STA 106 may be required to associate with the AP 104in order to send communications to and/or receive communications fromthe AP 104. In one aspect, information for associating is included in abeacon broadcast by the AP 104. To receive such a beacon, the STA 106may, for example, perform a broad coverage search over a coverageregion. A search may also be performed by the STA 106 by sweeping acoverage region in a lighthouse fashion, for example. After receivingthe information for associating, the STA 106 may transmit a referencesignal, such as an association probe or request, to the AP 104. In someaspects, the AP 104 may use backhaul services, for example, tocommunicate with a larger network, such as the Internet or a publicswitched telephone network (PSTN).

FIG. 2 shows an exemplary functional block diagram of a wireless device202 that may be employed within the wireless communication system 100 ofFIG. 1. The wireless device 202 is an example of a device that may beconfigured to implement the various methods described herein. Forexample, the wireless device 202 may comprise the AP 104, or one of theSTAs 106. The wireless device 202 may comprise a first wireless deviceor a second wireless device.

The wireless device 202 may include a processor 204 which controlsoperation of the wireless device 202. The processor 204 may also bereferred to as a central processing unit (CPU). Memory 206, which mayinclude both read-only memory (ROM) and random access memory (RAM), mayprovide instructions and data to the processor 204. A portion of thememory 206 may also include non-volatile random access memory (NVRAM).The processor 204 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 206. Theinstructions in the memory 206 may be executable to implement themethods described herein.

The processor 204 may comprise or be a component of a processing systemimplemented with one or more processors. The one or more processors maybe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system may also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions mayinclude code (e.g., in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 202 may also include a housing 208 that may includea transmitter 210 and/or a receiver 212 to allow transmission andreception of data between the wireless device 202 and a remote location.The transmitter 210 and receiver 212 may be combined into a transceiver214. An antenna 216 may be attached to the housing 208 and electricallycoupled to the transceiver 214. The wireless device 202 may also include(not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas.

The wireless device 202 may also include a signal detector 218 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 may alsoinclude a digital signal processor (DSP) 220 for use in processingsignals. The DSP 220 may be configured to generate a packet fortransmission. In some aspects, the packet may comprise a physicalprotocol data unit (PPDU).

The wireless device 202 may further comprise a user interface 222 insome aspects. The user interface 222 may comprise a keypad, amicrophone, a speaker, and/or a display. The user interface 222 mayinclude any element or component that conveys information to a user ofthe wireless device 202 and/or receives input from the user.

The various components of the wireless device 202 may be coupledtogether by a bus system 226. The bus system 226 may include a data bus,for example, as well as a power bus, a control signal bus, and a statussignal bus in addition to the data bus. Those of skill in the art willappreciate the components of the wireless device 202 may be coupledtogether or accept or provide inputs to each other using some othermechanism.

Although a number of separate components are illustrated in FIG. 2,those of skill in the art will recognize that one or more of thecomponents may be combined or commonly implemented. For example, theprocessor 204 may be used to implement not only the functionalitydescribed above with respect to the processor 204, but also to implementthe functionality described above with respect to the signal detector218 and/or the DSP 220. Further, each of the components illustrated inFIG. 2 may be implemented using a plurality of separate elements.

The wireless device 202 may comprise an AP 104, or a STA 106, and may beused to transmit and/or receive communications. That is, either AP 104,or STA 106, may serve as transmitter or receiver devices. Certainaspects contemplate signal detector 218 being used by software runningon memory 206 and processor 204 to detect the presence of a transmitteror receiver.

FIG. 3 is a timing diagram of one embodiment of a wireless communicationexchange 300 between an access point 104 and a station 106 a. FIG. 3depicts the AP 104 within a dense networking environment. For example,AP 104 may be within proximity of one or more other wireless devices,for example, at least station 106 b as shown. The timing diagram beginsat the left with the STA 106 a transmitting frame 1 302 to the AP 104.Because AP 104 is within a dense network environment, the transmissionof frame 1 may at least partially overlap with the transmission ofanother frame from another wireless device. As shown, STA 106 btransmits “Frame 2” 304 partially simultaneously with “Frame 1” 302.This partial simultaneous transmission may cause corruption of “Frame 1”302 when received by AP 104.

While Frame 1 may be at least partially corrupted when received by theAP 104, the AP 104 may still be able to determine some information fromthe corrupted frame. For example, in some cases, the device transmittingthe frame may be determined via a transmitter address field included inthe frame. Other relevant information may also be obtained from thecorrupted frame. For example, information such as any one or amodulation and coding scheme (MCS), transmission bandwidth information,duration information from the frame, and the intended receiver may bedetermined. In some cases, this information may be contained in one ormore portions of a PHY header of the frame. For example, in someaspects, a cyclic redundancy check (CRC) for the PHY header may indicatethe PHY header was received correctly. In response to this indication,some aspects may decode on one or more fields from the PHY header andrely on those values for further processing. In some aspects,information may also be decoded from a media access control (MAC) headerof the received frame. Information in the MAC header may or may not beprotected by a CRC or similar error correction mechanisms. Some aspectsmay utilize process 700, discussed below with respect to FIG. 8, toobtain certain information from a partially corrupted frame.

Because the “Frame 1” 302 is corrupted upon reception by AP 104, in theexample message exchange of FIG. 3, AP 104 transmits a negativeacknowledgment frame 306 to STA 106 a. In some aspects, a negativeacknowledgment may be indicated via an acknowledgment frame that has anyfield in a frame control field set to a non-zero value. For example, insome aspects, an acknowledgment packet with a retry field set to a valueof one may indicate a negative acknowledgment. The negativeacknowledgment frame 306 may also indicate that the AP 104 will protectfurther portions of the wireless communication exchange 300 by settingthe network allocation vector for a period of time sufficient or timenecessary to allow the exchange to complete. This indication may beprovided by setting one or more fields in the negative acknowledgmentframe 306 to particular value(s). For example, a duration field of thenegative acknowledgment frame 306 may indicate a necessary time forcompleting the wireless communication exchange.

The negative acknowledgment frame 306 may also include indications ofone or more suggested transmission parameters for the transmittingdevice (in this case, the STA 106 a) to use when retransmitting “frame1” 302. For example, the negative acknowledgment frame 306 may includean indication of a new modulation and coding scheme (MCS), transmissionbandwidth, or alternative channel information, such as channelallocation information or a suggestion to use a particular secondarychannel). In some aspects, the negative acknowledgment frame may alsoindicate an amount of time it will allocate for protection of theremaining portion of the wireless communication exchange 300.

Upon receiving the negative acknowledgment frame including theindications discussed above, the STA 106 a may defer additionaltransmissions on the wireless medium for a period of time. In someaspects, the negative acknowledgment frame 306 may indicate a time whenthe AP 104 will initiate protection by setting the network allocationvector (NAV). In these aspects, the STA 106 a may defer additionaltransmissions until at least the indicated time. In some aspects, theperiod of deferral may be fixed, or pre-negotiated.

While FIG. 3 shows the transmission of the negative acknowledgment frame306, in some aspects, negative acknowledgment frame 306 may not betransmitted. In these aspects, both STA 106 a and AP 104 may begincontending for the medium after frame 1 302 is transmitted. The AP 104may contend for the medium to send the message that would allow STA 106a to gain access to the medium for retransmitting “frame 1” 302, such asclear-to-send frame 308 discussed below. The STA 106 a may contend forthe medium in order to retransmit “frame 1” after the STA 106 adetermines the transmission was unsuccessful. Alternatively the STA 106a may contend for the medium in order to transmit a request to send(RTS) frame to the AP 104).

The AP 104 then starts contending for the wireless medium and thentransmits a clear-to-send (CTS) frame 308 when it wins contention. Insome aspects, the clear-to-send frame 308 may be addressed to the STA106 a. For example, an A1 field of the CTS frame 308 may identify theSTA 106 a (for example, by station address). The CTS frame 308 may setthe network allocation vector 315 for a period of time, for example, viaa duration field in the CTS frame 308. By setting the network allocationvector via the CTS frame, the receiver device (in this case, the AP 104)may enable the STA 106 a to retransmit Frame 1 under the protection fromcollisions provided by the NAV for the allocated duration of timeindicated in the CTS frame.

In some aspects, the CTS frame 308 may instead be any frame that wouldenable a reverse direction transmission (such as a reverse directionprotocol). In some aspects the frame may be a trigger frame (not shownin FIG. 3. The trigger frame may allocate resources for one or moreuplink stations (of which one is the STA 106 a), such that these STAsmay transmit their UL data as a response to the Trigger frame, after apredefined time (e.g., after SIFS) in the corresponding resources andusing the transmit parameters that are specified in the Trigger frameitself. The trigger frame may include a transmission schedule specifiedby the AP 104. In some aspects, the transmission schedule included inthe trigger frame may provide a schedule for one or more multi-userframes to be transmitted as an uplink transmission. In some aspects, thetrigger frame may be followed by one or more downlink frames that may bedestined for devices other than but also including the STA 106 a.

Upon determining that the AP 104 has provided protection for thewireless communication exchange 300, as indicated in the negativeacknowledgment frame 306 in certain embodiments, the STA 106 a thenretransmits “Frame 1” as packet 310. The acknowledgment 312 completeswireless communication exchange 300. Note that the AP 104 may transmitadditional frames to the 106 a (which may include “Frame 1”).

While FIG. 3 shows the AP 104 transmitting and receiving particularmessages, in some aspects, the devices shown in FIG. 3 may be reversed.For example, messages transmitted by the AP 104 in FIG. 3 may instead betransmitted by the STA 106 a. Similarly, messages transmitted by the STA106 a in FIG. 3 may instead be transmitted by the AP 104.

FIG. 4A is another timing diagram of one embodiment of a wirelesscommunication exchange 400 between an access point 104 and a station 106a. FIG. 4A depicts the AP 104 within a dense networking environment. Forexample, AP 104 may be within proximity of one or more other wirelessdevices, for example, at least station 106 b as shown.

The wireless communication exchange 400 begins with the STA 106 atransmitting a frame 402. In some aspects, the frame 402 may include amore data indication and/or may carry more than one data packet. In someaspects, one or more portions of the frame 402 may be corrupted. Whileframe 402 may be at least partially corrupted when received by the AP104, the AP 104 may still be able to determine some information from thecorrupted frame. For example, in some cases, the device transmitting theframe may be determined via a transmitter address field included in theframe. Other relevant information may also be obtained from thecorrupted frame. For example, information such as one or more of amodulation and coding scheme (MCS), transmission bandwidth information,duration information from the frame 402, and the intended receiver maybe determined. In some cases, this information may be contained in oneor more portions of a PHY header of the frame 402, such as in the L-SIG,or SIG-A or SIG-B of the PHY header. For example, in some aspects, a CRC(or a parity bit) for the PHY header may indicate that the correspondingportion of the PHY header it protects was received correctly. Inresponse to this indication, some aspects may decode on one or moreportions/fields from the PHY header and rely on those values for furtherprocessing. In some aspects, information may also be decoded from amedia access control (MAC) header of the received frame 402. Informationin the MAC header may or may not be protected by a CRC or similar errorcorrection mechanisms. Some aspects may utilize process 700, discussedbelow with respect to FIG. 8, to obtain certain information from thepartially corrupted frame 402.

The AP 104 then transmits a block acknowledgment message 404, at leastpartially acknowledging one or more of the data frames that arecontained in the frame 402. When one or more of the data frames includedin frame 402 are corrupted, the block acknowledgment message 404indicates that those particular frames were not received successfully.The block acknowledgment message 404 may also include a first indicationthat the STA 106 a will protect a remaining portion of the wirelesscommunication exchange 400. The block acknowledgment message 404 mayalso include a second indication of an estimated time when the STA 106 awill initiate the protection. For example, the indication of theestimated time may be a relative time offset from the transmission ofthe block acknowledgment message 404.

The block acknowledgment message 404 may also include indications of oneor more suggested transmission parameters for the transmitting device(in this case, the STA 106 a) to use when retransmitting frame 402. Forexample, the block acknowledgment message 404 may include an indicationof a new modulation and coding scheme (MCS), transmission bandwidth, oralternative channel information, such as channel allocation informationor a suggestion to use a particular secondary channel. In some aspects,the block acknowledgment message 404 may also indicate an amount of timethe AP 104 will allocate for protection of the remaining portion of thewireless communication exchange 400.

Upon receiving the block acknowledgment message 404 that indicates thefirst indication, the STA 106 a may defer transmissions of the wirelesscommunication exchange until at least the time indicated by the secondindication. Alternatively, the STA 106 a may defer for a predeterminedor negotiated period of time in response to receiving the firstindication.

The AP 104 then transmits the trigger frame 406. In some aspects, thetrigger frame 406 may include a transmission schedule for one or moreframes to be transmitted by the STA 106 a. In some aspects, thetransmission schedule may also schedule one or more frames to betransmitted by another device other than the STA 106 a. The triggerframe sets the network allocation vector 408 of devices receiving thetrigger frame 406 for a period of time T. In some aspects, the triggerframe 406 may be a clear-to-send (CTS) frame. For example, in somecases, the AP 104 may determine that it will only schedule a dataexchange with the STA 106 a, for example, when no other datatransmissions are pending with other devices associated with the AP 104.In this case, the AP 104 may determine to use a CTS frame to reserve theNAV instead of the trigger frame shown in FIG. 4A.

Upon determining that the AP 104 has protected a remaining portion ofthe wireless communication exchange 400, the STA 106 a transmits frame410 and frame 412. In some aspects, frame 410 may include a more dataindication while frame 412 does not. AP 104 then acknowledges frame 410and frame 412 via block acknowledgment 414, completing the wirelesscommunication exchange 400.

While FIG. 4A shows the AP 104 transmitting and receiving particularmessages, in some aspects, the devices shown in FIG. 4A may be reversed.For example, messages transmitted by the AP 104 in FIG. 4A may insteadbe transmitted by the STA 106 a. Similarly, messages transmitted by theSTA 106 a in FIG. 4A may instead be transmitted by the AP 104.

FIG. 4B is another timing diagram of one embodiment of a wirelesscommunication exchange between an access point 104 and a station 106 a.Timing diagram 450 depicts the station 106 a within a dense networkingenvironment. For example, station 106 a may be within proximity of oneor more other wireless devices.

The timing diagram begins with the STA 106 a transmitting a frame 452.The frame 452 may be transmitted during a contention period, when otherdevices may contend for access to the wireless medium along with the STA106 a. A collision between the frame 452 and another frame (not shown)may occur, such that frame 452 is at least partially corrupted whenreceived by the AP 104. However, the AP 104 may still be able todetermine that the frame 452 originated from the STA 106 a. For example,this determination may be made in some aspects using process 700discussed in more detail below.

In response to reception of frame 452, which may be partially corrupted,by the AP 104, the AP 104 may determine that protection from collisionsmay be provided for a remaining portion of a wireless communicationexchange with the STA 106 a. As discussed above with respect to FIG. 4A,despite the frame 452 being corrupted, some information may still beobtained by the receiving device AP 104. For example, in some cases, thedevice transmitting the frame may be determined via a transmitteraddress field included in the frame. Other relevant information may alsobe obtained from the corrupted frame 452. For example, information suchas one or more of a modulation and coding scheme (MCS), transmissionbandwidth information, duration information from the frame 452, and theintended receiver may be determined. In some cases, this information maybe contained in one or more portions of a PHY header of the frame 452.For example, in some aspects, a CRC for the PHY header may indicate thePHY header was received correctly. In response to this indication, someaspects of the AP 104 may decode on one or more fields from the PHYheader and rely on those values for further processing. In some aspects,information may also be decoded from a media access control (MAC) headerof the received frame 452. Information in the MAC header may or may notbe protected by a CRC or similar error correction mechanisms. Someaspects may utilize process 700, discussed below with respect to FIG. 8,to obtain certain information from the partially corrupted frame 452.

As shown in FIG. 4B, the AP 104 may respond by transmitting a triggerframe 454. In some aspects, the trigger frame may define a transmissionschedule. In some aspects, the transmission schedule may scheduletransmissions from the STA 106 a as part of a multi-user transmissionwhich is performed at a time after the trigger frame. The trigger framemay be transmitted by the AP 104 during a contention period. The triggerframe causes the NAV 456 to be set as shown, such that data can bereceived from the STA 106 a with a reduced risk of corruption fromcollisions. For example, the trigger frame 454 may include a durationfield indicating the length of the NAV 456. Note that while not shown inthe figure one or more STAs may be allocated to transmit during thescheduled transmission time using multi-user transmissions such asMU-MIMO or OFDMA.

At a time indicated by the trigger frame 454, the STA 106 a transmitsthree data packets 460 a-c, which are all included in a singleaggregated media protocol data unit (A-MPDU) 462. The AP 104 mayacknowledge one or more of the data packets 460 a-c with blockacknowledgment packet 470, which is also transmitted under theprotection provided by the trigger frame 454.

While FIG. 4B shows the AP 104 transmitting and receiving particularmessages, in some aspects, the devices shown in FIG. 4B may be reversed.For example, messages transmitted by the AP 104 in FIG. 4B may insteadbe transmitted by the STA 106 a. Similarly, messages transmitted by theSTA 106 a in FIG. 4B may instead be transmitted by the AP 104.

FIG. 5A shows an example wireless frame. The frame 500 includes one ormore of the following a legacy preamble 502, physical layer (PLCP)header 504 (which may contain one or more of an STF, LTF, SIG-A, SIG-Betc.), and one or more media access control (MAC) protocol data units(MPDU) 506, wherein the one or more MPDUs may be carried as part of anaggregated MPDU (A-MPDU), which is a structure that precedes each MPDUby an MPDU delimiter, specifying the length of the MPDU and otherinformation relevant for processing the MPDU, and a certain amount ofbytes (generally 0 to 3) follow each MPDU for padding purposes so thatthe overall length of the A-MPDU subframe is a multiple of 4 octets. Asan example, each MPDU 506 includes one or more of the following fields:a frame control field 507, duration id field 508, a first address field509, second address field 510, a Quality of Service (QOS) control field511, HT Control field and frame check sequence field 512, along withother fields. The frame control field 507 includes a protocol versionfield 512 a, type field 512 b, subtype field 512 c, ToDS field 512 d,FromDS field 512 e, more fragment field 512 f, Retry field 512 g, PwrMgt field 512 h, More Data field 512 i, Protected Frame (WEP) field 512j, and Order field 512 k (this would be the general structure whenprotocol version (PV) is zero (0)). Other structures are alsocontemplated (e.g., PV=1 frames have a different organization)

In some aspects, implementations may set the more fragment field 512 fto request that a receiver of the frame 500 initiate protection for adata communications exchange including the frame 500. For example, insome aspects, a message conforming with frame 500 described with respectto FIG. 5 may be transmitted, but includes only a portion of data for adestination device of the frame 500. Thus, in some aspects, the messagemay be sent with the more data field 512 i set to a value of one (1).However, to ensure reliable communication of a remaining portion of datatransmitted in subsequent frames, the transmitting device of the messagemay request the receiving device (i.e. a device identified by a receiveraddress of the frame 500), to initiate protection by setting the morefragment field 512 f. In some embodiments, the Retry field or any otherfield present in frame 500 can be used for this purpose.

The transmission parameters of the frame 500 are located in the PHYheader of the PPDU carrying one or more of the MPDUs, one of which canbe frame 500. The PHY header of the PPDU may contain one or more of thefollowing parameters (though not limited to) a modulation and codingscheme (MCS), bandwidth, number of spatial streams (NSS), PPDU duration,network allocation vector (NAV) duration, transmitter identifier,receiver identifier, direction of the frame (e.g., UL or DL), use ofLDPC or BCC, subchannel index within the bandwidth used for transmittingthe payload (i.e., the (A-)MPDU), SU/MU mode, BSS color (identifier),etc.

FIG. 5B shows an exemplary trigger frame 525. In some aspects, thetrigger frame 525 may be a clear to send frame. The trigger frame 525includes a frame control field 507, duration field 515, a receiveraddress field 516, a transmitter address field 517, a common info field518, and a transmission schedule 530.

The transmission schedule field 530 defines when transmissions may occurfrom one or more devices, identified by the device id fields 532 a-nduring the protection initiated by a device transmitting the triggerframe 525. Also included in the exemplary trigger frame 525 are channelinformation fields 534 a-n and optionally start time fields 536 a-n. Thechannel information fields 534 a-n may indicate one or more of a channelallocation information, modulation and coding scheme, spatial channelidentifiers, and/or frequency identifiers for use during a multi-usertransmission with other devices identified by the device identifierfields 532 a-n. The start time fields 536 a-n may provide a timereference indicating a time when transmissions to the device sending theframe 525 should be initiated. In some aspects, the start time may berelative to the time of transmission of the trigger frame 525. Incertain embodiments, as described above, the start time field can bepredetermined (e.g, after SIFS or PIFS) following the trigger frame.

The common info field 518 may include a length field 520 a, cascadeindication 520 b, he-sig-a information field 520 c, a CP and LTF Typefield 520 d, a trigger type field 520 e, and a trigger dependent commoninfo field 520 f. The length field 520 a of the Common Info field 518may indicate the value of the L-SIG Length field of the HE trigger-basedPPDU that is the response to the Trigger frame. If the cascadeindication field 520 b is 1, then a subsequent Trigger frame follows acurrent Trigger frame. Otherwise the Cascade Indication field 520 b iszero (0). The HE-SIG-A Info field 520 c may indicate the content of theHE-SIG-A field of the HE trigger-based PPDU response. The TBD bits inHE-SIG-A of the HE trigger-based PPDU that may be implicitly known byall responding STAs can be excluded. The CP and LTF Type field 520 d mayindicate the CP and HE-LTF type of the HE trigger-based PPDU response.The Trigger Type field 520 e indicates the type of the Trigger frame.The Trigger frame can include an optional type-specific Common Info andoptional type-specific Per User Info.

FIG. 5C is an exemplary response frame to a frame that was at least inpart a corrupted frame. In some aspects, the response frame 550 may takethe form of an acknowledgment frame, block acknowledgment frame, ornegative acknowledgment frame. The response frame 550 may include theframe control field 507, duration field 552, receiver address field 554,protection indication field 556, start time field 558, transmissionparameters field 560, and frame check sequence field 562. In someaspects the response frame may be a control response frame that carriesan HT Control field, where in the HT Control field may carry thetransmission parameters and the other fields.

In some aspects, the response frame 550 may be transmitted in responseto receiving a frame requesting protection for a wireless communicationexchange. For example, in some aspects, the response frame 550 may betransmitted in response to receiving a frame 500 with the more fragmentfield 512 f set to a value of one (1) (or another value), requestingprotection for a remaining portion of a wireless communication exchange.

The protection indication field 556 may indicate whether a transmitterof the response frame 550 will cause a network allocation vector (NAV)to be set to protect a remaining portion of a wireless communicationexchange. For example, in some aspects, the response frame 550 mayacknowledge a data packet having a more data field, such as more datafield 512 i in frame 500 of FIG. 5A, with a value set to one (1) (oranother value is other aspects). If the protection indication field 556is set to a one, it may indicate the transmitter of the response frame550 will cause the NAV to be set for a time period estimated to besufficient to complete the data transfer of data that is part of thedata communication exchange. The data communication exchange may includethe transfer of data from a data sending device to a data receivingdevice. The data sending device may be addressed by the response frame550 (for example, by the receiver address field 554 of the responseframe 550 (not shown) may identify the data sending device). The datareceiving device may be the device transmitting the response frame 550.

The transmission parameters field 560 may include at least one or moreof a modulation and coding scheme (MCS) 564 a, transmission bandwidthinformation 564 b, and channel information 564 c such as channelallocation information. In some aspects, values in the transmissionparameters field 560 may indicate how a subsequent transmission,performed under the protection indicated by protection indication field556, is to be performed.

FIG. 6 is a method of wireless communication. In some aspects, process600 may be performed by either a station or an access point. Forexample, process 600 may be performed by the AP 104 described withrespect to FIGS. 3 and 4A-B above. In some aspects, the process 600 maybe performed by the wireless device 202, described above with respect toFIG. 2. For example, instructions stored in the memory 206 may configurethe processor 204 to perform one or more of the functions discussedbelow with respect to process 600.

Process 600 may allow a device receiving one or more frames from anotherdevice that would otherwise be transmitted/received during a contentionperiod to instead initiate protection for those frames by causing anetwork allocation vector to be set. Once the network allocation vectoris set, the frames may then be transmitted/received under the protectionfrom collisions provided by the NAV. This protection may be especiallyvaluable when the receiving device is within a dense networkenvironment, where the probability of packet collisions is relativelyhigh. By initiating protection of the wireless communication exchange, areceiver can better ensure successful completion of the communicationexchange at an acceptable packet loss/efficiency level. Note that whilethe descriptions refer to a NAV protection mechanism, in some otheraspects, the protection may be provided by any other protectionmechanism, such as setting the duration field of the L-SIG field of theframe initiating the exchange, etc.

In block 605, a first wireless frame is received. The first wirelessframe is received by a receiving device. The first wireless frame ispart of a wireless communication exchange between a transmitting deviceand the receiving device. A wireless communication exchange may includean exchange of messages between two devices, the receiving device and atransmitting device, with each of the messages having an associationwith each other. For example, a data packet and an acknowledgment of thedata packet may form a wireless communication exchange in some aspects.In some other aspects, a series of data frames including one or moreadditional data frames, with each eventually including a more dataindication, except for perhaps a last data frame of the series, alongwith one or more acknowledgment frames acknowledging the transmitteddata frames may form another wireless communication exchange in someaspects. In some aspects the acknowledgment packets may be blockacknowledgment frames. In some aspects, the wireless communicationexchange may be a series of data packets exchanged in both uplink anddownlink between an access point and one or more associated STAs. Insome aspects, a wireless communication exchange duration may beequivalent to a duration of a remaining transmission opportunity.

The first wireless frame may be received during a contention period onthe wireless network, in that the frame is not transmitted/receivedwhile a network allocation vector is set for one or more of thereceiving device and the transmitting device. In some other aspects, thenetwork allocation vector may be set when the first wireless frame istransmitted/received. For example, the device transmitting the firstwireless frame may have performed a RTS/CTS exchange prior totransmitting the first wireless frame. However, one or more stations onthe wireless medium may not have received the RTS/CTS exchange and thusdo not have their network allocation vector set. For example, a stationwithin proximity of the receiving device may not have its networkallocation vector set, such that it may transmit at least partiallyconcurrently with the transmission/reception of the first wirelessframe. In some aspects the first wireless frame may be exchanged during(re-)association or be part of a negotiation between two devices.

In some aspects, block 605 includes determining that the received firstwireless frame includes one or more errors. In some aspects, thedetermination that the received first wireless frame includes errors maycause the receiving device to initiate protection of a remaining portionof the wireless communication exchange as described below.

In some aspects, block 605 includes determining that the received framecontained a buffer size field in a QoS control field, such as the QOScontrol field 511 in FIG. 5A, indicating a non-zero value. In someaspects, this determination may cause the receiving device to initiateprotection of a remaining portion of the wireless communication exchangeas described below. One or more of the functions discussed above withrespect to block 605 may be performed by one or more of the receiver 212and/or processor 204.

In some aspects, block 605 includes decoding the first wireless frame todetermine the transmitted device requests that the receiving deviceprotect the wireless medium for a remaining portion of the wirelesscommunication exchange. For example, in some aspects, the received framemay substantially conform to the format of frame 500, shown above withrespect to FIG. 5A. In these aspects, a device performing process 600may decode the more fragment field 512 f to determine if a transmittingdevice of the frame 500 requested that the receiving device initiateprotection for a data communications exchange including the frame 500.As mentioned above the field can be the Retry field, or any other fieldin the frame (potentially it could be in the PHY header as well).

In some aspects, block 605 includes decoding the frame to determine oneor more transmission parameters.

The transmission parameters of the received frame may be located in aphysical (PHY) header of the received frame. The PHY header of thereceived frame may include one or more of the following parameters(though not limited to) MCS, bandwidth, number of spatial streams (NSS), PPDU duration, NAV duration, a transmitter identifier, a receiveridentifier, a direction of the frame (e.g., UL or DL), use of lowdensity parity check (LDPC) or binary convolutional code (BCC),subchannel index within the bandwidth used for transmitting the payload(i.e., the (A-)MPDU), SU/MU mode, and/or Basic Service Set (BSS) color(identifier).

In some aspects, these parameters may include a request for thereceiving device to initiate medium access and/or initiate protection ofat least a portion of one or multiple communication exchanges asdescribed below. Some aspects the request may include a periodicity, anumber of communication exchanges to be initiated and other parametersthat help the receiving device determine the duration of time forprotecting the one or more communication exchanges.

In some aspects of block 605, a response to the first wireless frame,such as a third wireless frame, is transmitted. The response wirelessframe may be generated to indicate that the receiving device will enableprotection for a remaining portion for the wireless communicationexchange. For example, in some aspects, the response frame may conformto the format shown in FIG. 5C as response frame 550. In some aspects,the protection indication field 556 may be used to indicate whether thereceiving device will enable protection.

Enabling protection includes transmitting one or more messages to causea network allocation vector (NAV) to be set, such that the wirelessmedium is reserved for transmissions associated with the wirelesscommunication exchange. The indication in the response frame may be inthe form of one or more bits, allocated into one or more fields of theresponse frame, that have particular values. The particular values maybe predefined, for example, via a wireless communication standard, toprovide the indication described above. For example, in some aspects,the response frame may conform to the format shown in FIG. 5C asresponse frame 550. In some aspects, the protection indication field 556may be used to indicate whether the receiving device will enableprotection. In some aspects, the more fragment field 512 f may be set toa particular value to indicate the receiving device will enableprotection as described above. Other fields may also be used for thispurpose in various aspects. In received frame aspects that includetransmission parameters as discussed above, the response may includeconfirmation of transmission parameters or provide alternativeparameters, for example but not limited to a modulation and codingscheme (MCS), number of spatial streams (NSS), PPDU duration, aperiodicity and number of frames that may be sent to provide protectionto the device transmitting the first frame.

In some aspects, the response frame is generated to include a secondindication of an estimated time when the receiving device will initiateprotection of the remaining portion of the wireless communicationexchange. For example, in some aspects, the second indication is a timeoffset from the time the response frame is transmitted, for example, asshown by start time field 558 of FIG. 5C.

In some aspects, the response frame is generated to indicate one or moretransmission parameters for the transmitting device to use whenretransmitting at least a portion of the first wireless frame. Forexample, the response frame may indicate an updated MCS, bandwidthparameters or alternative channel information, such as a suggestion touse a particular secondary channel or subchannel. An example of this isshown above with respect to transmission parameters field 560, andtransmission bandwidth fields 564 a-c. In some aspects, the responseframe is generated to indicate a duration of time for which protectionwill be established. For example, in some aspects, the duration may bestored in the duration field 552.

In some aspects, the response frame is generated as an acknowledgmentframe, a block acknowledgment frame, or a negative acknowledgment frame.A negative acknowledgment frame in some aspects may be indicated via anacknowledgment frame that has one or more fields in a frame controlfield that are set to non-zero values. For example, in one aspect, anegative acknowledgment frame is generated to have a retry field 512 gof the frame control field 507 set to a value of one. In some aspects, anegative acknowledgment frame or a block acknowledgment frame isgenerated when block 605 determines that the received frame includeserrors. For example, a block acknowledgment frame may selectively notacknowledge the received frame if it included errors. In some aspects,one or more of the functions discussed above with respect to block 605may be performed by the transmitter 210 and/or processor 204. In someaspects, multiple response frames may be generated, one or more of whichas part of a (re-) negotiation, and one or more as part of responses toreceived frames transmitted by the requesting devices. In some aspect noresponse frame may be generated. In some aspects, the transmitter mayinterpret the lack of a response frame as an implicit acknowledgment. Insome aspects the response frame contains an HT Control field.

In block 615, a second frame is transmitted during a contention period.The second frame may be generated as a clear-to-send frame in someaspects. For example, the type/subtype field 512 b/512 c of the framecontrol field 507 may be set to values defined in the 802.11 standardthat indicate the frame is a clear to send frame. The second frame maybe addressed to the transmitting device, for example, via an addressfield 509 or 516 in a media access control header of the clear-to-sendframe. The second wireless frame protects the wireless medium for a timeperiod. For example, in some aspects, the time period is determined bythe receiving device to be adequate (greater than or equal to) a timerequired to complete a remaining portion of the wireless communicationexchange. The time period may be of a duration sufficient to protect aremaining portion of the wireless communication exchange from packetcollisions.

For example, in aspects where the second wireless frame is aclear-to-send frame, a duration field (such as duration field 528) ofthe clear-to-send (CTS) frame may indicate a period of time during whichthe network allocation vector should (or shall) be set by STAs to whichthe CTS frame is not addressed. In these aspects, the duration field 528may indicate a period of time during which receiver device to which theCTS frame is addressed may transmit one or more frames addressed to thetransmitter of the second wireless frame. In some aspects, the device towhich the CTS is addressed may transmit to any other STA during thatduration of time. In some aspects the device to which the CTS isaddressed should discard or otherwise ignore any previous NAV setting.

In some other aspects, the second frame may be generated as a triggerframe. For example, the trigger frame may have type/subtype values inthe frame control field 507 that identify the frame as a trigger framevia an 802.11 standard (and not as a clear to send frame for example).The trigger frame may also include an indication of a time period duringwhich the network allocation vector should be set by STAs that are notthe intended receivers of the trigger frame. In some aspects, thetrigger frame is generated to include a transmission schedule. Thetransmission schedule may indicate timing parameters associated with thetransmission of one or more frames to be transmitted by the device thattransmitted the first wireless frame. In some aspects, the receivingdevice may receive packets from multiple devices during the time periodallocated for protection by the trigger frame. In some aspects, thereceiving device may receive the multiple packets from multiple devicesusing multi-user mode, such as MU-MIMO or OFDMA. For example, as shownin FIG. 5B, the trigger frame 525 may include a series of informationindicating schedule information for a particular device. For example,the device identifier field 532 indicates that information is for aparticular device. Channel information field 534 indicates which channela transmission should be performed on, and start time field 536indicates when the transmission should begin. The fields 532, 534, 536may be of a fixed length such that a device receiving the trigger frame525 can parse through a number of fixed length records to see if it isidentified by any of the fields 532 a-n. In some aspects, one or more ofthe functions discussed above with respect to block 615 may be performedby one or more of the processor 204 and/or the transmitter 210.

In block 620, a remaining portion of the wireless communication exchangeis received from the transmitting device under the protectionestablished by the second frame. In some aspects, block 620 may includereceiving one or more data packets. For example, in some aspects, iferrors were detected in the first wireless frame and a negativeacknowledgment was sent to the transmitting device as described abovewith respect to some aspects of block 605, then block 620 may includereceiving a retransmission of the first wireless frame and acknowledgingthe retransmission. If the first wireless frame included a more dataindication, then block 620 may include receiving one or more additionaldata frames, with one or more of these additional data frames alsoincluding a more data indication (except perhaps a last packet). Theadditional data frames may then be acknowledged via one or more blockacknowledgments as part of block 620. The reception and/or transmissionof frames in block 620 occurs under the protection from collisionsprovided by the NAV set as a result of functions performed during block615. One or more of the functions discussed above with respect to block620 may be performed by a combination of one or more of the processor204, receiver 212, and/or transmitter 210.

FIG. 7 is a flowchart of a method of wireless communication. In someaspects, process 700 may be performed by either a station or an accesspoint. For example, process 700 may be performed by the STA 106 adescribed with respect to FIGS. 3, 4A and 4B. In some aspects, theprocess 700 may be performed by the wireless device 202, described abovewith respect to FIG. 2. For example, in some aspects, the memory 206 maystore instructions that configure the processor 204 to perform one ormore of the functions discussed below with respect to process 700. Insome aspects, the process 700 is performed by a device transmitting datato a receiving device, which is performing process 700.

Process 700 may allow a device transmitting data to receive anindication from a device receiving the data that the receiving devicewill initiate protection of data transfer from the transmitting deviceto the receiving device. For example, ordinarily, one or more of theframes would be transmitted during a contention period. However, usingthe disclosed methods and systems, the transmitting device receives anindication from the receiving device that the receiving device willinitiate protection for those frames (for example, by causing a networkallocation vector (NAV) to be set). This indication is received in aframe that is different than a frame actually requesting the networkallocation vector (NAV) to be set.

Once the network allocation vector is set, the transmitting deviceresumes its transmission of frames to the receiving device. Theseremaining frames are transmitted under the protection from collisionsprovided by the NAV set by the receiving device. This protection may beespecially valuable when the receiving device is within a dense networkenvironment, where the probability of packet collisions near thereceiving device is relatively high. By initiating protection of thewireless communication exchange between the transmitting device andreceiving device, the receiving device can increase the likelihood ofcompletion of the communication exchange at an acceptable packetloss/efficiency level. Note that while the description above and belowgenerally refers to protection by setting a network allocation vector(NAV), other aspects may provide protection via any other protectionmechanism. For example, some aspects may set the duration field of anL-SIG field of a frame initiating the communication exchange in order toprovide protection.

In block 705, a first wireless frame is transmitted on a wirelessmedium. The frame is transmitted to a receiving device by a transmittingdevice. The first wireless frame forms at least a portion of a wirelesscommunication exchange between the transmitting device and the receivingdevice. For example, in some aspects, the first wireless frame may beone of a series of data packets, which, along with correspondingacknowledgments or block acknowledgments for the one or more datapackets, form a wireless communication exchange. In these aspects, someof the data packets or one or more wireless frames may include a moredata indication. In some aspects, the first wireless frame does notinclude a more data indication. In some aspects, a wirelesscommunication exchange may be equivalent to a duration of a remainingtransmission opportunity. In some aspects, one or more of the functionsdiscussed above with respect to block 705 may be performed by thetransmitter 210 and/or the processor 204.

In some aspects, the first wireless frame is generated to include one ormore transmission parameters. For example, the first wireless frame maybe generated to indicate a request for a device receiving the firstwireless frame to initiate medium access and/or initiate protection forat least a portion of one or more communication exchanges. In someaspects, the request may indicate a periodicity, a number ofcommunication exchanges to be initiated by the receiving device, andother parameters that may assist the receiving device in determining aduration of time that protection should be established for one or morecommunication exchanges.

The transmission parameters of the first message may be located in aphysical (PHY) header of the first message. The PHY header of the firstmessage may include one or more of the following parameters (though notlimited to) MCS, bandwidth, number of spatial streams (NSS), PPDUduration, NAV duration, a transmitter identifier, a receiver identifier,a direction of the frame (e.g., UL or DL), use of low density paritycheck (LDPC) or binary convolutional code (BCC), subchannel index withinthe bandwidth used for transmitting the payload (i.e., the (A-)MPDU),SU/MU mode, and/or Basic Service Set (BSS) color/identifier.

In some aspects of block 705, a response frame is received from thereceiving device. The response frame may indicate the receiving devicewill initiate protection for a remaining portion of the wirelesscommunication exchange. For example, in some aspects, the response framemay conform to the format of response frame 550, discussed above withrespect to FIG. 5C. In some aspects, the response frame is decoded asone of an acknowledgment, block acknowledgment, or negativeacknowledgment of the first wireless frame. In response to receiving anegative acknowledgment from the receiving device, the transmittingdevice may record or mark the first wireless frame as requiring aretransmission once the protection is established. If the first frame isacknowledged by the response frame (for example, by a blockacknowledgment or a regular acknowledgment), then the first frame may bemarked as completed and may not be retransmitted by the transmittingdevice. In some aspects, one or more of the functions discussed abovewith respect to block 705 may be performed by the receiver 212 and/orthe processor 204.

Some aspects that receive a third wireless fame, such as a responseframe as described above, may defer additional communications relatingto the wireless communication exchange until the protection indicated bythe response frame is established. This may include, in response to thethird wireless frame, deferring further transmissions until the NAV isset. For example, if the response frame indicates an estimated time forprotection to be established (for example, via start time field 558),the transmitting device may defer additional communications relating tothe wireless communication exchange until at least the time indicted. Insome aspects, a fixed or predetermined deferral period may be used.

In some aspects, the response frame may be decoded to determine anamount of time for which protection will be established. For example, insome aspects the duration field 552 may be decoded to determine anamount of time for which protection will be established. In someaspects, one or more transmission parameters may be decoded from theresponse frame. For example, in some aspects, the transmissionparameters field 560 shown in FIG. 5C may be decoded. In some aspects,the transmission parameters field 560 may be at least in partialresponse to transmission parameters included in the first wirelessframe. For example, the response frame 550 may confirm one or more of aperiodicity and number of frames that may be sent by the receivingdevice under protection provided by the transmitting device.

The response may also be decoded to determine one or more of an updatedmodulation and coding scheme (MCS) (such as provided by transmissionbandwidth field 564 a), transmission bandwidth parameters (such asprovided by transmission bandwidth field 564 b) or alternative channelinformation (as provided by transmission bandwidth field 564 c), such aschannel allocation information or a suggestion to use a particularsecondary channel may be decoded from the response frame. In someaspects, the receiving device may utilize these transmission parametersin future communications with the device transmitting the responseframe.

In some aspects, multiple response frames may be received. In someaspects, one or more of these multiple response frames may be part of arenegotiation, and one or more may be part of responses to receivedframes transmitted by the transmitting device. In some other aspects, noresponse frame may be received. In these aspects, lack of a responseframe may be determined to be an implicit acknowledgment.

One or more of the functions discussed above with respect to block 705may be performed, in some aspects, by a combination of one or more ofthe processor 204 and/or transmitter 210.

In block 715, a second wireless frame protecting the wireless medium isreceived from the receiving device. In some aspects, this secondwireless frame may conform with the trigger frame 525 shown in FIG. 5B.In some aspects, the second wireless frame is decoded as a clear-to-send(CTS) frame or a trigger frame. For example, in some aspects, theclear-to-send (CTS) frame may be received by the transmitting device inblock 715. If the CTS frame is not addressed to the transmitting device,the CTS frame indicates a network allocation vector (NAV) should be set.In some aspects, a duration field 528 of the clear-to-send frameindicates a time period the NAV should be set. The duration field 528may be decoded by the transmitting device to determine how long its ownnetwork allocation vector should be set. If the CTS frame is addressedto the transmitting device (i.e. the device receiving the CTS frame),the CTS is an indication that protection is now established, and aremaining portion of the pending wireless communication exchange can becompleted during the protection period. A duration field 528 of the CTSframe may indicate how much time is available to complete the wirelesscommunication exchange.

In some aspects, a trigger frame is received in block 715, indicatingthat protection has been established for a remaining portion of thewireless communication exchange. In some aspects, the trigger frame isdecoded to determine a transmission schedule, such as transmissionschedule 530 shown in FIG. 5B. The transmission schedule 530 mayindicate a time when one or more frames are to be transmitted to thereceiving device. For example, as shown in trigger frame 525, thetransmission schedule 530 may indicate channel information 534 and/orstart time information 536 for a device identified by the device idfield 532. In some aspects, information for multiple devices may bepresent in then transmission schedule 530. The trigger frame may alsoinclude an indication of a duration of the protection for the wirelesscommunication exchange, i.e. how long the network allocation vector(NAV) should be set by devices to which the trigger frame is notaddressed.

In block 720, a remaining portion of the wireless communication exchangeis completed under the protection established by the frame received inblock 715. In some aspects, once protection is established, completingthe wireless communication exchange may include retransmitting one ormore data packets to the receiving device. In some aspects, theretransmission of the one or more data packets may be based ontransmission parameters decoded from the optional response framediscussed above with respect to block 705. In some aspects, if thetransmitting device previously received a negative acknowledgment forthe first wireless frame transmitted in block 705, completing thewireless communication exchange may include retransmitting the firstwireless frame and receiving an acknowledgment for the first wirelessframe from the receiving device.

In some aspects, completing transmission of the wireless communicationexchange may include transmitting one or more additional data framesincluding “more data” indications to the receiving device, and receivingcorresponding acknowledgments, such as one or more block acknowledgmentsfor the one or more transmitted data frames from the receiving device.In these aspects, the first wireless frame may have been generated witha more data indication as well.

In some aspects, completing transmission of the wireless communicationexchange may also include transmission of one or more packets to otherdevices besides the receiving device. For example, in some aspects, thetrigger frame discussed above may identify a time period when atransmission should be initiated to the receiving device. During theindicated time, the transmitting device may also transmit data to otherdevices, for example, via the use of multi-user multiple input multipleoutput (MU-MIMO) or orthogonal frequency division multiple access(OFDMA).

In some aspects, one or more of the functions discussed above withrespect to block 720 may be performed by one or more of the processor204 and/or transmitter 210 and/or receiver 212.

FIG. 8A shows one organization of a wireless frame. Frame 800 includes aphysical header 805, and one or more of the following: a media accesscontrol (MAC) header 815, payload 820, and a frame check sequence (FCS)field 825, and padding (not shown). The frame 800 includes a variety ofdata that may be used to determine whether the frame is addressed to aparticular device that may receive the frame. For example, in someaspects the physical header 805 may contain one or more of a partialassociation identifier for the addressed (intended) receiving device, apartial association identifier for the device transmitting the frame, abasic service set color indication, typically a basic service setidentifier of a device transmitting the frame, and/or an indication ofwhether the frame is UL or DL.

The media access control (MAC) header 815 may also include one or moreindications of an intended receiver of the frame. For example, the mediaaccess control header 815 may include an address field (A1) indicating astation address or other identifier of the intended receiver device(i.e. the device to which the frame is “addressed”). The MAC header 815may also include an address field indicating a station address or otheridentifier of the transmitting device. The MAC header 815 may alsoinclude an address field indicating the basic service set identifier ofthe transmitting device. One or more of these fields in the frame 800may be used to determine an intended receiver of the frame 800 in theevent that the frame 800 becomes partially corrupt due to, for example,a collision with another frame on a wireless medium. An example of sucha process is described below with respect to FIG. 9.

FIG. 8B shows another organization of a wireless frame 850. The frame850 includes a physical header 855, a plurality of A-MPDU subframes,shown in the example of FIG. 8B as A-MPDU subframe 860 a and A-MPDUsubframe 860 b, and optional padding 865. Each of the A-MPDU subframesincluded in frame 850 may include an MPDU delimiter field 870, an MPDU875 (including a MAC header, payload, and frame check sequence field,which are not shown in FIG. 8B), and an optional pad field 880.

The frame 850 includes a variety of data that may be used to determinewhether the frame is addressed to a particular device that may receivethe frame. For example, in some aspects the physical header 855 maycontain one or more of a partial association identifier for theaddressed (intended) receiving device, a partial association identifierfor the device transmitting the frame, and a basic service set colorindication, typically a basic service set identifier of a devicetransmitting the frame, an indication whether the frame is UL or DL.

Each of the media access control (MAC) headers 815 in the frame 850 mayalso include one or more indications of an intended receiver of theframe. For example, the media access control header 815 may include anaddress field (A1) indicating a station address or other identifier ofthe intended receiver device (i.e. the device to which the frame is“addressed”). The MAC header 815 may also include an address fieldindicating a station address or other identifier of the transmittingdevice. The MAC header 815 may also include an address field indicatingthe basic service set identifier of the transmitting device. One or moreof these fields in the frame 850 may be used to determine an intendedreceiver of the frame 800 in the event that the frame 850 becomespartially corrupt due to, for example, a collision with another frame ona wireless medium. An example of such a process is described below withrespect to process 900.

FIG. 9 is a flowchart of a method of determining whether a frame thatincludes errors is addressed to a device receiving the frame. Forexample, although errors caused by packet collisions may corrupt atleast portions of a received frame, other portions of the frame mayremain uncorrupted. By decoding the uncorrupted portions of the frame, adevice receiving the frame may be able to determine whether thecorrupted frame was addressed to the receiving device or not. Thisinformation may be used to determine whether the receiving device shouldinitiate protection for a communication exchange between itself and adevice transmitting the corrupted frame, as discussed above.

In some aspects, process 900 may be performed by any of the wirelessdevice 202 of FIG. 2, AP 104 or STA 106 a-b of FIGS. 1, and 3-4A-B. Forexample, in some aspects, each of the blocks discussed below may beperformed by the processor 204. In some aspects, the frame discussedbelow may substantially conform with one or more of the characteristicsof the frame 800 or frame 850, discussed above with respect to FIGS.8A-B.

In block 905, a frame received by a receiving device may be determinedto include one or more errors. For example, in some aspects, a framecheck sequence field, such as any one of frame check sequence field 513,535, 562, or 825 of FIGS. 5A-C or FIGS. 8A-B, respectively may be usedto verify the integrity of the received frame as is known in the art.This integrity check may determine that the received frame includes atleast one error. The frame received in block 905 may be transmitted by atransmitting device, which may be an access point or a station invarious aspects.

Decision block 910 determines whether the frame includes an identifieridentifying the receiving device. In some aspects the identifier may beat least a portion of an association identifier, such as a partialassociation identifier. For example, the partial association identifierof the receiving device, as illustrated in FIGS. 8A-B, may be includedin a physical header 805 or 855 of the frames 800 and 850 respectively.The receiving device may determine whether a partial associationidentifier (AID) or (PAID) included in the frame is at least a partialmatch to an AID assigned to the receiving device during a previousassociation with an access point. In some aspects the (partial) AIDincluded in the frame is at least a partial match to a MAC address ofthe receiving device.

In some aspects, a partial match may require one or more bits of the(partial) AID in the frame to match corresponding bits in an AIDpreviously assigned to the receiving device. In some aspects, all bitsof the partial AID of the frame must match a previously assigned AID inorder for a match to be determined in decision block 910. In otheraspects, fewer than all the bits may be required to match. For example,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 bits of the (partial)AID in the frame must match a previously assigned AID for a match to bedetermined in decision block 910.

Functions performed in block 910 may vary across embodiments. Forexample, in some aspects, the identifier referenced in block 910 mayactually be comprised of at least portions of multiple fields includedin the received frame. For example, in some aspects, a PHY header of thereceived frame may not have the identifier of the receiving device asdiscussed with respect to block 910. In some aspects, the received framemay include a transmitter association identifier (e.g. partial or fullassociation identifier) field and/or a basic service set color field,and/or an uplink/downlink indication. In some aspects, the receivingdevice may determine the received frame is intended for or addressed tothe receiving device based on a combination of one or more of thesefields.

If the frame does not include at least a partial match with a previouslyassigned AID, process 900 moves to block 930, which determines the frameis not addressed to the receiving device. Otherwise, in some aspects,decision block 910 may also inspect one or more media access controlheaders included in the frame to determine whether an address fieldidentifies the receiving device. For example, as illustrated in frame800 of FIG. 8A, the media access control header 815 may include anaddress field (A1) that identifies an intended receiver of the frame. Ifthis identifier identifies the receiving device (i.e. the deviceperforming process 900), then decision block 910 may determine a matchhas occurred. If no correctly received MAC header address field (such asan address field 509 of FIG. 5A, 516 of FIG. 5B, or the A1 field shownin MAC header 815 identifies the receiving device, process 900 moves toblock 930, which determines the frame is not addressed to the receivingdevice.

Otherwise, process 900 moves to decision block 915, which determineswhether the frame includes identification of a device transmitting theframe, and whether that device is a “known” transmitting device. A knowntransmitting device may be a device that the receiving device (i.e. thedevice performing process 900) has previously exchanged frames with. Forexample, any device with which the receiving device is associated wouldbe a known transmitting device.

In some aspects the transmitter identifier may be at least a portion ofan association identifier or at least a portion of a MAC address of aknown transmitting device. For example, the device performing process900 may maintain a data store of association identifiers and/or MACaddresses of devices it has previous communicated with. If atransmitter's association identifier (e.g. partial or full associationidentifier) (TAID) value included in the received frame (such as thepartial TAID shown in the physical header 805 of frame 800 of FIG. 8A)does not at least partially match a known transmitting device, process900 moves from decision block 915 to block 930, which determines thereceived frame is not addressed to the receiving device. Otherwise, ifthe TAID of the received frame is at least a partial (or complete) matchwith a known transmitting device, then some aspects of process 900 mayalso inspect a media access control (MAC) header included in the frameto determine whether an address field, such as an A2 field (such assecond address field 510 shown in FIG. 5A) identifies a knowntransmitting device. If no correctly received MAC header address field(such as the second address field 510) identifies a known transmittingdevice in these aspects, process 900 moves from decision block 915 toblock 930, which determines the received frame is not addressed to thereceiving device. Otherwise, process 900 moves to decision block 920.

Decision block 920 determines whether the frame includes a basic serviceset identifier which is equivalent to at least a portion of thereceiving device's basic service set identifier. If it does not, process900 moves to block 930, which determines the received frame is notaddressed to the receiving device. If the frame does include at least aportion of the basic service set (BSS) identifier of the receivingdevice, process 900 moves to block 925, which determines the frame isaddressed to the receiving device. In some aspects the basic service set(BSS) identifier is included in the physical (PHY) header, such as aphysical layer convergence protocol (PLCP) header. Some aspects of block925 may infer one or more additional values from the frame. For example,a transmission opportunity (TXOP) duration specified in the PHY header,for example in an L-SIG, SIG-A/B/C field, a length of a PHY Service DataUnit (PSDU) as specified in the PHY header, for example in the L-SIG,SIG-A/B/C field, a modulation and coding scheme (MCS), and otherparameters useful for future scheduling of the protected TXOP may beinferred from the received frame's PHY header or other portions of theframe.

Some aspects of process 900 further include block 930, which responds tothe transmitting device based on the received frame being addressed tothe receiving device. For example, in some aspects, block 930 mayinclude one or more functions of process 600, discussed above withrespect to FIG. 6. For example, in some aspects, the received frame ofblock 905 may be the same frame as the first wireless frame referencedin block 605.

While process 900 shown in FIG. 9 and described above provides at leastone example implementation, other implementations of determining whethera frame that includes errors is addressed to a device receiving theframe are also contemplated. For example, in some aspects, an accesspoint may be able to determine whether a frame is addressed to it in adifferent manner than a station. For example, in some aspects, if anaccess point can successfully decode that the received frame is anuplink frame (for example, via an uplink/downlink indicator in theframe), and a basic service set color indication in the frame is a matchfor the access point's color, then the access point may determine theframe is addressed to it. In some aspects, the access point may decodean association identifier (e.g. partial or full association identifier)of the transmitter of the received frame from the received frame. If thedecoded association identifier field corresponds to records ofassociation identifiers the access point has used to communicate with anassociated station, then this determination may contribute to adetermination that the received frame was intended for or addressed tothe access point. In some aspects, the access point may decode areceiver association identifier field (e.g. partial or full associationidentifier) from the received frame. If the value in this field matchesan association identifier of the access point, the associationidentifier field may contribute to a determination that the receivedframe is intended for or addressed to the access point.

A station may determine a received frame is intended for or addressed toit using some of the same fields used by an access point but may alsoutilize different fields. For example, in some aspects, a station maydetermine whether a partial association identifier of an intendedreceiver, and a BSS color field (identifier of the basic service set),of a downlink frame indicates the frame is addressed to the station. Forexample, if the association identifier (e.g. partial or full associationidentifier) of the receiver field corresponds to the station's partialassociation identifier, and the BSS color field of the received framematches a BSS color of an associated access point, the station maydetermine the received frame is addressed to it. In some other aspects,a station may rely only on BSS color indication in a downlink frame. Insome aspects, the station may also decode a transmitter address of thereceived frame, if it is not corrupted. The station may determinewhether the transmitter address corresponds to a device (e.g. accesspoint) with which the station is associated. If it does, this mayfurther confirm that the received frame was intended for or addressed tothe station.

In some of the above aspects, the station may decode an associationidentifier of the transmitter (e.g. partial or full associationidentifier) in the received frame. If the decoded transmitter partialassociation identifier field corresponds to records of partialassociation identifier of transmitters the station has used tocommunicate with an associated access point, then this determination maycontribute to a determination that the received frame was intended foror addressed to the station.

In some aspects, process 900 may include transmitting a clear-to-sendframe or a trigger frame. In some aspects, the clear-to-send or triggerframe may be addressed to the receiving device (in that a destinationaddress field identifies the receiving device). By transmitting theclear-to-send frame or the trigger frame, the receiving device maysignal to the transmitting device that it should allocate resources fortransmission of frames, including a retransmission of the frame receivedin block 905, to the receiving device.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like. Further, a “channel width” as used herein may encompass ormay also be referred to as a bandwidth in certain aspects.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-e, and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations. Forexample, the functional means may include a processor and memoryoperably coupled to the processor, the memory storing instructions thatconfigure to the processor to perform the described functions.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components or anycombination thereof designed to perform the functions described herein.A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium may comprisenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium may comprisetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware or any combination thereof. If implemented in software, thefunctions may be stored as one or more instructions on acomputer-readable medium. A storage media may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Software or instructions may also be transmitted over a datacommunications medium. For example, if the software is transmitted froma website, server, or other remote source using a coaxial cable, fiberoptic cable, twisted pair, digital subscriber line (DSL), or wirelesstechnologies such as infrared, radio, and microwave, then the coaxialcable, fiber optic cable, twisted pair, DSL, or wireless technologiessuch as infrared, radio, and microwave are included in the definition ofdata communications medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of wireless communication on a wirelessmedium, comprising: receiving, by a receiving device, a first wirelessframe from a transmitting device during a contention period, the firstwireless frame forming a portion of a wireless communication exchangebetween the transmitting device and the receiving device; transmittingduring the contention period, a second wireless frame indicating anetwork allocation vector for the wireless medium should be set for atime period of a duration sufficient to protect a remaining portion ofthe wireless communication exchange from packet collisions; andreceiving, via the receiving device, the remaining portion of thewireless communication exchange from the transmitting device during thetime period.
 2. The method of claim 1, wherein the wirelesscommunication exchange includes one or more wireless frames with a moredata indication, and corresponding acknowledgments for the one or morewireless frames.
 3. The method of claim 1, further comprisingdetermining that the first wireless frame includes an error, wherein thetransmitting of the second wireless frame is in response to thedetermining.
 4. The method of claim 1, further comprising transmittingto the transmitting device, in response to the first wireless frame, athird wireless frame indicating that the receiving device will protectthe wireless medium for the remaining portion of the wirelesscommunication exchange.
 5. The method of claim 1, further comprisingdecoding the first wireless frame to determine the transmitting devicerequests that the receiving device protect the wireless medium for theremaining portion of the wireless communication exchange; andtransmitting the second wireless frame in response to the determination.6. The method of claim 4, further comprising generating the thirdwireless frame to indicate a time when the receiving device will protectthe wireless medium.
 7. The method of claim 4, further comprisinggenerating the third wireless frame to indicate one or more transmissionparameters for the transmitting device.
 8. The method of claim 7,wherein the one or more transmission parameters include one or more of amodulation and coding scheme, a transmission bandwidth, or channelinformation, or a channel allocation for the transmission of theremaining portion of the wireless communication exchange.
 9. Anapparatus for wireless communication on a wireless medium, comprising: areceiver configured to receive a first wireless frame from atransmitting device during a contention period, the first wireless frameforming at least a portion of a wireless communication exchange betweenthe transmitting device and the apparatus; and a transmitter configuredto transmit during the contention period, a second wireless frameindicating a network allocation vector for the wireless medium is setfor a time period of a duration sufficient to protect a remainingportion of the wireless communication exchange from packet collisions;and completing the wireless communication exchange during the timeperiod.
 10. The apparatus of claim 9, wherein the wireless communicationexchange includes one or more wireless frames with a more dataindication, and corresponding acknowledgments for the one or morewireless frames.
 11. The apparatus of claim 9, further comprising aprocessor configured to determine that the first wireless frame includesan error, wherein the transmitter is further configured to transmit thesecond wireless frame in response to the determining.
 12. The apparatusof claim 9, further comprising transmitting to the transmitting device,in response to the first wireless frame, a third wireless frameindicating that the apparatus will transmit the second wireless frame.13. The apparatus of claim 9, further comprising a processor configuredto decode the first wireless frame to determine the transmitting devicerequests that the apparatus set the network allocation vector for thetime period for the duration sufficient to protect the remaining portionof the wireless communication exchange from packet collisions.
 14. Theapparatus of claim 12, further comprising a processor configured togenerate the third wireless frame to indicate one or more transmissionparameters for the transmitting device, wherein the one or moretransmission parameters include one or more of a modulation and codingscheme, a transmission bandwidth, channel information, and a channelallocation.
 15. The apparatus of claim 12, further comprising aprocessor configured to generate the third wireless frame as one of ablock acknowledgment or a negative acknowledgment.
 16. The apparatus ofclaim 12, further comprising a processor configured to generate thethird wireless frame to indicate a time when the apparatus will transmitthe second wireless frame.
 17. The apparatus of claim 12, furthercomprising a processor configured to generate the third wireless frameto indicate one or more transmission parameters.
 18. The apparatus ofclaim 12, further comprising a processor configured to generate thethird wireless frame to indicate a duration of time for which thenetwork allocation vector will be set.
 19. The apparatus of claim 9,further comprising a processor configured to determine a time necessaryto complete the wireless communication exchange, and generate the secondwireless frame to protect the wireless medium for at least the timenecessary.
 20. The apparatus of claim 9, wherein the transmitter isfurther configured to transmit the second wireless frame protecting thewireless medium by transmitting a clear-to-send frame to thetransmitting device, the clear-to-send frame indicating a durationgreater than or equal to a time necessary to transmit the remainingportion.
 21. A method of wireless communication over a wireless medium,comprising: transmitting, by a transmitting device, a first wirelessframe to a receiving device during a contention period, the firstwireless frame comprising a portion of a wireless communication exchangebetween the transmitting device and the receiving device; receiving asecond wireless frame from the receiving device, the second wirelessframe indicating a network allocation vector should be set for a timeperiod; and completing, by the transmitting device, the wirelesscommunication exchange with the receiving device during the time period.22. The method of claim 21, further comprising generating the firstwireless frame to comprise an indication of a request for the receivingdevice to set the network allocation vector.
 23. The method of claim 21,further comprising: receiving, from the receiving device, a thirdwireless frame different than the second wireless frame, the thirdwireless frame comprising an indication that the receiving device willrequest the network allocation vector be set; and in response to thethird wireless frame, deferring further transmissions of the wirelesscommunication exchange until the network allocation vector is set. 24.The method of claim 23, further comprising decoding the third wirelessframe to determine one or more of a confirmation of transmissionparameters included in the first wireless frame, and one or moretransmission parameters for transmission to the receiving device. 25.The method of claim 21, further comprising: generating the firstwireless frame as a data frame with a more data indication, whereincompleting transmission of the wireless communication exchange comprisestransmitting one or more additional data frames and receivingcorresponding acknowledgments for the one or more additional dataframes.
 26. An apparatus for wireless communication over a wirelessmedium, comprising: a transmitter configured to transmit a firstwireless frame to a receiving device during a contention period, thefirst wireless frame comprising a portion of a wireless communicationexchange between the apparatus and the apparatus; a receiver configuredto receive a second wireless frame indicating a network allocationvector should be set for a time period; and completing the wirelesscommunication exchange with the receiving device during the time period.27. The apparatus of claim 26, further comprising a processor configuredto generate the first wireless frame to comprise an indication of arequest for the receiving device to set the network allocation vector.28. The apparatus of claim 26, further comprising a processor, whereinthe receiver is further configured to receive a third wireless framecomprising an indication that the receiving device will set the networkallocation vector, and the processor is configured to, in response tothe third wireless frame, defer further transmissions of the wirelesscommunication exchange until the network allocation vector is set. 29.The apparatus of claim 28, wherein the processor is further configuredto decode the third wireless frame to determine one or more of aconfirmation of transmission parameters included in the first wirelessframe, and one or more transmission parameters for transmission to thereceiving device.
 30. The apparatus of claim 26, further comprising aprocessor configured to generate the first wireless frame as a dataframe with a more data indication, wherein completing transmission ofthe wireless communication exchange comprises transmitting one or moreadditional data frames and receiving corresponding acknowledgments forthe transmitted data frames.